Hydraulic unit

ABSTRACT

A hydraulic unit, comprising a tank case for accommodating a hydraulic medium, in which a hydraulic pump is disposed and is adjoined by a valve block on which at least one controllable valve is arranged in a supply line to a hydraulic user, and an electric motor which has a stator housing on the side of the valve block that is opposite the tank case, and the shaft of which is coupled to the hydraulic pump via the valve block, characterized in that the valve block and stator housing are integrally formed.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not applicable.

BACKGROUND OF THE INVENTION

Hydraulic units usually are composed of a driving motor, a pump, a hydraulic fluid tank, and a valve block. The driving motor commonly is an electric motor. The hydraulic unit requires to be designed as being compact if the spatial conditions are restricted. Therefore, it has become known already to immerse the hydraulic pump into the hydraulic medium within a tank case and connect the tank case to the valve block. The stator housing of the motor is flanged to the valve block on the opposite side. The shaft of the electric motor extends through the valve block to the pump in order to drive it. The valve block contains bores for accommodating valves to realize a hydraulic circuit for the supply to at least one hydraulic user. Compact hydraulic units of this type specifically are used in industrial trucks which provide for little constructional space. For example, the hydraulic pump feeds a lifting cylinder, a hydraulic steering mechanism or other users.

During the manufacture and assembly of such hydraulic units, it is necessary to fit or bolt together the individual components such as the motor, valve block, valves, pump, tank, and filter. Therefore, the effort in manufacture accordingly is large.

It is the object of the invention to provide a hydraulic unit in which the cost of manufacture may be lowered significantly.

BRIEF SUMMARY OF THE INVENTION

In the inventive hydraulic unit, the valve block and stator housing are integrally formed, e.g., from a cast steel.

In the inventive hydraulic unit, the stator housing does not need a flange for being bolted to the valve block. In addition, it becomes unnecessary to work on such a flange and the valve block for the purpose of an intimate connection of the two components. Hence, this allows the fabrication of the hydraulic unit at a clearly lower expenditure in manufacture and assembly.

According to an aspect of the invention, the valve block, on its side facing the tank case, has an axial annular collar which engages the interior of the tank case approximately fittingly while the end of the tank case that faces the valve block engages a recess at the outside of the annular collar, whereby the outsides of the stator housing and tank case become approximately flush with each other.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention will be described in more detail below with reference to an embodiment thereof.

FIG. 1 shows the outlines a hydraulic unit of the invention.

DETAILED DESCRIPTION OF THE INVENTION

While this invention may be embodied in many different forms, there are described in detail herein a specific preferred embodiment of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiment illustrated

FIG. 1 illustrates a stator casing 10 for an electric motor which is not shown in greater detail. At its upper end, the stator casing 10 is closed by a cover 12 on which terminals 14, 16 are provided for the supply of power. As can be seen, the stator casing 10 is formed integrally with a valve block 18. In the figure, a valve casing is shown at 20 which engages the valve block 18 via an opening. The valve 20 is controllable and exhibits a terminal to connect a possible feed line to a user.

The side of the valve block 18 which is opposite the stator housing 10 has formed thereon an annular collar 22. Its outer diameter is slightly smaller than is the outer diameter of the valve block 18 so as to provide a recess. This recess is engaged by a thickened edge 24 of a tank case 26. The tank case 26 is formed from a plastic material, for example. The two components are joined to each other by means of a tensioning strap which is placed around the thickened end 24 and gets tensioned. This is not illustrated in the drawing.

The tank case 26 has arranged therein a pump, which is not shown in greater detail. The pump draws a hydraulic medium out of the tank case 26 from the lower region and feeds the medium to the valve 20. The shaft, not shown, of the electromotor, not shown, extends through the valve block 18 to the pump, not shown, in order to drive it. The hydraulic medium is returned to the tank 26 via a filter. In the figure, an oblique connecting sleeve 28 is shown through which a filter cartridge can be inserted and may be fixed in place by means of a screw cap 30. The filter cartridge serves for filtering impurities out of the hydraulic medium while the medium flows back to the tank 26 from the user.

The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to”. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims.

Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim 1 should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below.

This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto. 

1. A hydraulic unit, comprising a tank case for accommodating a hydraulic medium, in which a hydraulic pump is disposed and is adjoined by a valve block on which at least one controllable valve is arranged in a supply line to a hydraulic user, and an electric motor which has a stator housing on the side of the valve block that is opposite the tank case, and the shaft of which is coupled to the hydraulic pump via the valve block, characterized in that the valve block (18) and stator housing (10) are integrally formed.
 2. The hydraulic unit according to claim 1, characterized in that the valve block, on its side facing the tank case (26), has an axial annular collar which engages the interior of the tank case (26) in an approximately fitting manner while the end of the tank case (26) that faces the valve block (18) engages a recess at the outside of the annular collar (26), causing the outsides of the stator housing and tank case to be approximately flush with each other.
 3. The hydraulic unit according to claim 1, characterized in that the valve block (18) and stator case (10) are formed from a cast metal. 